In general, a dye image obtained by photographic processing of a silver halide color photographic material comprises an azomethine dye or an indoaniline dye formed by the reaction between a coupler and an oxidation product of an aromatic primary amine developing agent. The thus obtained color photographic image is not always stable against light or wet heat and is liable to suffer discoloration or color change when exposed to light or preserved under high temperature and high humidity conditions for a long time, resulting in serious deterioration of the image quality.
Discoloration of dye images is virtually a fatal defect for recording materials. It has conventionally been proposed to overcome this defect by selection of couplers which are less prove to discoloration, the use of a discoloration inhibitor which prevents discoloration of dye images due to exposure to light, or the use of an ultraviolet absorbent which prevents image deterioration due to ultraviolet radiation.
Among other results, use of discoloration inhibitors produces considerable effects to prevent image deterioration. Known discoloration inhibitors include, for example, hydroquinones, hindered phenols, catechols, gallic esters, aminophenols, hindered amines, etc., as well as ethers or esters of these compounds in which the phenolic hydroxyl group is silylated, acylated or alkylated, and metal complexes, as described in U.S. Pat. Nos.3,935,016, 3,982,944, and 4,254,216, British Patent 2,066,975, U.S. Pat. Nos. 3,700,455, 4,360,589, and 3,457,079, Japanese Patent Publication No. 21144/81, and U.S. Pat. Nos. 3,336,135, 4,268,593, 4,050,938, and 4,241,155.
Although the metal complexes are recognized as highly effective to prevent discoloration or color change of dye images, they inevitably cause coloring of the white background of dye images after development processing due to their own color. Therefore, they have failed to sufficiently meet the increasing demand for high image quality.